Oscillation system



Aug. 16 1932. 'TERMAN 1,871,632

o'scnLA'rIoN SYSTEM Filed NOV. 19, 1929 IN VEN TOR.

rade 110K 6 91mm,

'iarrangement embodying the Patented Aug. 16, 1932 STATES FREDERICK I]. TERMAN, OF STANFORD UNIvERsITYpcAiIFORN IA, ASSIGNOR RADIO, IHQ, OF NEW YORK, N. Y.,

vA CORPORATION OF DELAWARE oscILLA'rIoiv SYSTEM Application filed November 19, 1929. Serial 110.408391.

My invention relates broadly to electron tube oscillators, and more particularly to an arrangement of circuit for electron tube oscillators for producing sustained electrical oscillations.

One of the objects of my invention is to provide an electron tube circuit arrangement for an oscillation system in which sustained oscillations at constant frequency may be produced and wherein the plate electrode is maintained at high negative potential.

Another object of my invent-ionv is to provide a circuit arrangement for an electron tube oscillator in which a voltage reducing reaction exists between the plate circuit and the grid circuit for establishing oscillations of constant frequency.

Still another object of my invention is to provide a circuit arrangement for an electron tube oscillator, wherein the plate and grid circuits are connected in such manner that a reduction in voltage occurs between the input and output circuits in the course of the feed-back operation of the electron tube circuits for the production of constant frequency oscillations.

A further object of my invention is to provide a circuit for a piezo electric crystal c011- trolled oscillator, wherein the piezo electric crystal element ground to a predetermined frequency characteristic is connected between the cathode and plate electrodes of the r electron tube system and an oscillator cir-s gridcuit connected between the cathode and electrodes of the oscillator system for the production of constant frequency oscillations.

Other and further objects of my invention will be more fully understood from the specic fication hereinafter following by reference to the accompanying drawing in which:

Figure 1 isa. diagrammatic illustration of a simplified form of the oscillator circuit of my invention; and Fig. 2 shows a circuit principles of my invention in which the oscillations produced in the electron tube circuits are sustained at constant frequency by means of a piezo electric crystal element.

In the oscillator system of my invention I To WIRED V employ an electron tube connected in an inverted manner by which theelectron tube may function as an oscillator.- I employ the principlesset forth tion entitled Electron tubecircuit, Serial No. 405,363 filed November 7,1929. A .voltage reducing action is obtained betweenthe plate and grid circuits of the oscillator-system in the manner set forth in the aforesaid application. The plate portion of the inductance which may be common to the plateand grid circuits is therefore many times greater than the grid portion of the inductance. 'I have found that a ratio of 8 to 1 between the inductance in the plate and the inductance in thegrid circuit is a desirable proportion when using a UK 171A tube. A high negative potentialis impressed upon the plate electrode and a positive potential applied to the grid electrode; The ability of the inverted electron tube to oscillate depends upon the reflex mutual conductance. The higher this value, the easier itis for oscillations to more fully my applicatake place. The circuit arrangement of my invention is particularly adapted for operation under control of a piezo electric crystal system, and when the circuit is piezo electrically controlledthe piezo electric crystal elementis con'nectedbetween the plate and cathode electrodes, as will be more fully de scribed hereinafter. V

Referring to the drawing in more detail, reference character 1 designates the electron tube employedv in the circuit ofmy invention where the tube includes cathode 2, grid 3 and plate 4. The'cathode is'suitably heated from any desired source tem 5', regulated through resistor 6. input circuit to the oscillator includes potential source 7, having its negative The high potential 'connectedto plate electrode 4:, and

its positive terminal connected to the output circuit end 8 of inductance 9. A tap 10 connects to the cathode 2 at a position along the inductance 9 where a largernumber of turns are included in the output circuit than are included in the input at 11. The inputcircuit includes the portion 11 of inductance 9 and the source of potential 12having its positive terminal connected such as battery sys- 7 the .7

circuit as represented to grid electrode 3. The inductance-S) has its terminal ends 8 and 14: bridged by means of condenser 15. For the best conditions of operation I have found that with a positive potential of 66 volts on the grid 3 and a negative potential of 152 volts on the plate when using a (IX-371 tube, an oscillatingscurrent of 200 milliamperes at. approxlmately 36 kilo;

cycles was obtained in a low resistance circuit at constant frequency. j l l In Fig. "2 I have shown the method employed for constant frequency control utilizing a piezo electric crystal element 16 con-' nected between electrodes17 and 18 to the input circuit of the oscillator across plate electrode 4 and cathode 2. The plate 4t is negatively biased from battery 7 through'resistance 19. The output circuit in the piezo electric crystalcontrolled joscillator may include the adjustably tuned system v19 constituted by inductance QOand variable condenser 21. I have found thatthe circuit arrangement of'myinvention' operates as an oscillator for the production of oscillations of extremely constant frequency.

While I have described'certain preferred embodiments ofmy invention, I desire that it be understoodthat modifications may be made and that no limitations upon my invention are intended other than are imposed by the'scope'of theappended claims.

What I claim as new-anddesire to secure by Letters Patent ofthe United States is as follows: i I

1. An oscillation (system comprising an electron tube including" a cathode, a grid and a a plate, an input circuit including said plate and cathode, an output circuit including said grid and cathode, means for charging said anode at a negative potential, means for charging said grid at a positive potential, and

a frequency determining vibratile element connected in said input circuit. V I

2. An oscillation system comprising an electron tube having a cathode, a grid and a plate, an input circuit interconnecting said plate and cathode, an output circuit interconnecting said grid andcathode, means in said I output circuit for'cha'rging said grid atposifive-potential, means in said input circuit'for charging said plateat negative potential, an inductance connected in said. output circuit,

and a frequency controlling vibratile element 7 connected in said input circuit for the production of oscillations at constant frequency.

' In testimony whereof I -aflix. my signature.

FREDERICK, E. TERMAN. 7' 

